Equus Kilo - Crystal Empire [Frozen North] - Castle of Love [Formerly the Castle of Fear] - Flurry Heart's Room
Once upon a time in the Frozen North, there was a princess named Cadence who had a little filly named Flurry Heart. The filly would cry and mope all the time. No amount of soothing and gifts would ever make her happy.
Princess Cadence called upon all the wise ponies of the Crystal Empire and beyond to find a cure to Flurry Heart's depression. Some tried to use magic and others medicine. Nothing worked.
A wise Zebra eventually came and told Cadence that she must find a truly happy pony and take a lock of their mane. By giving her daughter the lock, she would become happy as well. With nothing to lose, the Princess went on the mission to find such this mythically gay pony.
First, she met with Filthy Rich. The stallion claimed to be the happiest of the land for he had no want of money. He owned multiple mansions and had several successful businesses. His only daughter would always have the best food and toys.
However, Cadence inspected the stallion's happiness and found it wanting. Filthy Rich worked tirelessly to maintain his businesses and constantly feared losing everything due to a blunder. His wealth had, instead of making his life easier and happier, made Filthy Rich endlessly busy and anxious.
Second, the Princess met with her elder Princess - Celestia. The diarch of Equestria had more power than any pony. All loved and feared her. She spent her days leading with unquestioned authority. Due to her magic, her body never aged, so Celestia could remain beautiful until the end of time, all things equal.
However, Cadence inspected the mare's happiness and found it wanting. Celestia's power was a shame. Centuries of combat had only made her weaker psychologically. Celestia's guilt for banishing Luna for her own crime had disconnected her from the Elements of Harmony. When she fought, Celestia couldn't bring forth the full power she had due to memories of using it excessively against those who didn't deserve death. Deep down, Celestia knew she was nopony others should love or fear. That is why she relied on proxies to fight battles she had procrastinated on for over a millennia. In other words, power and eternal youth did not happiness bring.
Third, the royal mare met with the scholar Starswirl the Bearded. The stallion had seen the future and no knowledge was beyond him. Starswirl was the one could prophesied Luna's fall from grace and her return. It was said he had nothing to fear for he could predict any evil and had the magic ready to defeat it. Many believed him to be a happy stallion because he lived in certainty.
However, Cadence inspected the stallion's happiness and found it wanting like all the rest. With certainty came boredom. While Starswirl did fear anything, he never had any happy surprises. His friends were all well and protected, but the lack of spontaneity ate at him him. Starswirl wished he could go back to days where he didn't know everything, so he could again experience of learning something and being excited for what would happen next. This he could not do as the bearded stallion had a responsibility to his kingdom. He must keep protecting it to the day he inevitably died. A fortune once cast, after all, was absolute.
Cadence walked back home. The princess given up all hope. She felt certain that she would never find a truly happy pony from whom to take a lock of their mane. Along the way, however, she heard a happy tune coming from an roadside orchard. The tune carried had an airy soul befitting a pony without a care in the world. The Princess ran towards to source to find a whistling earth pony mare who wore a simple hat.
After talking to the farmer, Cadence found the mare the living definition of gaiety.
The Princess asked politely that the earth pony remove her hat. The mare complied to reveal: the truly happy pony was bald.